1. Field of the Invention
The present invention relates to semiconductor devices comprising image sensing or pickup elements.
2. Related Background Art
Optical detection of wide wavelength ranges is widely performed in a variety of systems including, but not limited to, spectrum analyzers and/or material analysis/contaminant detection apparatus based on absorption of light in specified wavelength bands.
For example, a semiconductor device with two-stage structure is shown in Japanese Patent Laid-Open No. 304182/1997. FIG. 10 is a diagram showing a system configuration of such prior art device, which is adaptable for detection of the color shades of rice grains that have been passed through each channel 105. While the target body being detected is denoted by reference numeral 127, an image of this target body 127 is focused by a condensing lens 119 to fall onto a semiconductor device consisting essentially of semiconductor image sensing or pickup elements 122A, 123A of the two-stage structure. More specifically, the above-identified Japanese document discloses therein the two-stage structure semiconductor device which includes a first photodetector (Si photodiode) 122A having high sensitivity in a visible light range and a second photodetector (InGaAs array sensor) 123A, wherein these elements are stacked or laminated over each other.